Nichols et al.: Spatial and temporal distribution of Eubalaena glacialis in Cape Cod Bay 
277 
70° W 
12-25 January 
! | > 69.04 (top 5%) 
MBB = 28.95-69.03 ( 75th— 95th percentile) 
= 12.3 1-28.94 ( 50th— 75th percentile ) 
= 5.37-12.30 ( 25th— 50th percentile) 
= 0.01-5.36 (< 25th percentile) 
= 0 (effort > 0) 
no effort 
Figure 5 
North Atlantic right whale ( Eubalaena glacialis ) sightings per unit effort (SPUE; 
whales/1000 km of survey effort) in Cape Cod Bay, by two-week period (A-L), 1998-2002. 
SPUE values are separated by quartiles, representing the top, second highest, third, 
and bottom quarters of the distribution. The upper quarter is further partitioned by 
identifying the top 5% of all values. 
The significant interannual variations in mean SPUE 
and timing of annual SPUE maxima were likely due to 
physically forced changes in available food resources. 
An atypical physical environment and zooplankton 
assemblage were observed in 2002, compared to 2000 
and 2001 (DeLorenzo Costa et al., 2006; Jiang et al., 
2007), which corresponded to the order-of-magnitude 
difference in 2002 right whale SPUE compared to that 
in 2000. Further comparisons of right whale distribu- 
tional data and environmental variables should be con- 
ducted to assess the causes of the patterns observed. 
Despite the interannual SPUE variability, the signifi- 
cant within-season and interannual spatial stability of 
right whale occurrence lends support to the use of 
these data to define the spatial extent of management 
measures. 
The results of the aerial surveys and SPUE analysis 
confirmed earlier findings of Hamilton and Mayo (1990) 
in that peak occurrence of right whales in the study ar- 
ea occurred from February through April. The patterns 
observed in both studies are largely consistent with 
earlier, more qualitative descriptions of right whale 
